Cody W van Dijk

University of Manitoba, Winnipeg, Manitoba, Canada

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Publications (8)12.79 Total impact

  • Cody W. van Dijk, Ming Sun, Jennifer van Wijngaarden
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    ABSTRACT: The ground state rotational spectra of 2,3-, 2,4-, 2,5-, 2,6- and 3,5-difluoropyridine have been investigated using both Balle-Flygare type Fourier transform microwave (FTMW) and chirped pulse Fourier transform microwave (cp-FTMW) spectroscopies. In addition to the parent species, the spectra of the 13C and 15N singly-substituted isotopologues were recorded in the 5-23 GHz region in natural abundance. The rotational constants determined from heavy atom substitution were used to determine the bond lengths and angles within the pyridine backbone of each species. A more pronounced deviation from the pyridine ring geometry is observed when the fluorine substituent is ortho to nitrogen which is consistent with ab initio predictions of the structures at the MP2 (6-311G++2d2p) level of theory. Analyses of the observed 14N hyperfine splitting patterns provided a key source of information about the electronic structure surrounding the nitrogen atom as a function of the various fluorine substitutions. Together, the experimental results are consistent with bonding models that involve subtle changes in the hybridization of the carbon atom that bears the fluorine substituent as well as donation of electron density from the lone pair of fluorine into the π-system of pyridine.
    Journal of Molecular Spectroscopy 10/2012; · 1.67 Impact Factor
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    ABSTRACT: Foreign double-stranded RNA (dsRNA) generated during the normal course of the viral life cycle serves as a key infection recognition element by proteins of the innate immune response. To circumvent this response, all adenoviruses synthesize at least one highly structured RNA (VA(I)), which, after processing by the RNA silencing machinery, inhibits the innate immune response via a series of interactions with specific protein partners. Surprisingly, VA(I) positively regulates the activity of the interferon-induced 2'-5'-oligoadenylate synthetase (OAS) enzymes, which typically represent a key mechanism whereby host-cell protein translation is attenuated in response to foreign dsRNA. We present data investigating the regulation of the OAS1 isoform by VA(I) derivatives and demonstrate that a processed version of VA(I) lacking the terminal stem behaves as a pseudo-inhibitor of OAS1. A combination of electrophoretic mobility shift assays, dynamic light scattering, and non-denaturing mass spectrometry was used to quantitate binding affinity and characterize OAS1:VA(I) complex stoichiometry. Enzyme assays characterized the ability of VA(I) derivatives to activate OAS1. Finally, the importance of RNA 5'-end phosphorylation state is investigated, and it emphasizes its potential importance in the activation or inhibition of OAS enzymes. Taken together, these data suggest a plausible strategy whereby the virus produces a single RNA transcript capable of inhibiting a variety of members of the innate immune response.
    Journal of Molecular Biology 06/2012; 422(5):635-49. · 3.91 Impact Factor
  • Cody W. Van Dijk, Ming Sun, Jennifer Van Wijngaarden
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    ABSTRACT: The ground state rotational spectra of a series of fluorinated pyridines have been measured using a Balle-Flygare Fourier transform microwave (FTMW) spectrometer and a chirped pulse Fourier transform microwave (cp-FTMW) instrument between 8 and 23 GHz. The species under investigation include 2- and 3-fluoropyridine as well as 2,3-, 2,4-, 2,5-, 2,6- and 3,5-difluoropyridine. In addition to the parent species, the spectra of the 13C and 15N singly-substituted isotopologues were recorded in natural abundance and used to calculate relevant geometric parameters of the pyridine ring backbone. Analysis of the 14N hyperfine structure provided an additional source of information about the electronic structure surrounding the nitrogen atom as a function of fluorine substitution. The experimental results are compared with those from ab initio theory and are consistent with a bonding model that involves donation of electron density from fluorine into the π-system of pyridine.
    06/2012;
  • [show abstract] [hide abstract]
    ABSTRACT: The ground state rotational spectra of 2-fluoropyridine and 3-fluoropyridine have been investigated using both Fourier transform microwave (FTMW) and chirped pulse Fourier transform microwave (cp-FTMW) spectroscopies. In addition to the parent species, the spectra of the (13)C and (15)N singly substituted isotopologues were recorded in the 8-23 GHz region in natural abundance. The rotational constants determined for the seven isotopologues of each were used to calculate relevant geometric parameters including the bond distances and angles of the pyridine ring backbone. The derived structures show a more pronounced deviation from the pyridine ring geometry when the fluorine substituent is ortho to nitrogen which is consistent with ab initio predictions at various levels of theory. Analysis of the (14)N hyperfine structure provided an additional source of information about the electronic structure surrounding the nitrogen atom as a function of fluorine substitution. Together, the experimental results are consistent with a bonding model that involves hyperconjugation whereby fluorine donates electron density from its lone pair into the π-system of pyridine.
    The Journal of Physical Chemistry A 03/2012; 116(16):4082-8. · 2.77 Impact Factor
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    ABSTRACT: The ground state pure rotational spectrum of silacyclobutane (SCB) (c-SiH(2)C(3)H(6)) has been investigated using both Fourier transform microwave (FTMW) and chirped pulse Fourier transform microwave (cp-FTMW) spectroscopies. Spectra of the (13)C, (29)Si, and (30)Si singly substituted isotopologues, in natural abundance, were recorded in the 6-24 GHz region along with those of the normal species. The ring inversion tunnelling splitting in the ground vibrational state was resolved and analyzed to determine the energy splitting of the two states: 75.7260(19) MHz. Structural analysis based on heavy atom substitution provided accurate geometric parameters including the bond lengths, bond angles, and ring puckering angle of the SCB ring backbone.
    The Journal of Physical Chemistry A 08/2011; 115(31):8650-5. · 2.77 Impact Factor
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    ABSTRACT: The pure rotational spectra of the ground states of silacyclobutane (SCB) and silacyclopentane (SCP) were measured in a supersonic jet in the 6-24 GHz range using Fourier transform microwave spectroscopy and the chirped-pulse variant of this technique. Heavy atom isotopic substitution for the silicon and each of the carbon atoms within the rings enabled the accurate determination of the RS and R0 structural parameters of the ring backbones of both SCB and SCP. For SCB, splitting due to ring inversion in the ground state has been observed and analyzed.
    06/2011;
  • Journal of Molecular Spectroscopy 01/2010; 259(1):56–59. · 1.67 Impact Factor
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    ABSTRACT: The rotational spectrum of silacyclobutane (c-C{_3}H{_8}Si) has been measured between 8 and 24 GHz using Fourier transform microwave spectroscopy. Although the microwave spectrum was previously reported, the current study is the first observation of tunneling splitting in the ground state due to ring puckering. The observed transitions within each tunneling state obey a-type selection rules and c-type transitions that connect the inversion states have also been observed. The rotational constants determined were used to model the rotational structure of several vibrational bands of silacyclobutane including the weak ring puckering mode at 157 cm^{-1}. The far infared spectrum of silacyclobutane was recorded using the far infrared beamline at the Canadian Light Source and includes multiple tunneling doubled bands. The ongoing analysis of the incredibly rich vibrational spectrum of silacyclobutane will be discussed. W. C. Pringle J. Chem. Phys. 54 (4979), 1971.
    06/2009;